Examples of Photos The Physics Classroom says: It's a common question on physics tests: Splat!
"A very unfortunate bug collides with the windshield of a high speed car. What encounters the greatest force - the bug or the windshield."
Don't fall for this one! Think Newton's third law! Think "equal". For every action, there is an EQUAL and opposite reaction. The force of the bug on the windshield is EQUAL to the force of the windshield on the bug. EQUAL
Skeptics will (and should) ask, "How can that be? The bug splatters all over the windshield and there is no noticeable detection in the speed of the car." With this statement, the subject was changed from Newton's third law to Newton's second law. The forces on the two interacting objects are equal, but the accelerations resulting from those forces are not. The bug encounters an enormous acceleration - not because of a greater force, but rather because of its relatively smaller mass. And as for the splattering - bugs do that sort of thing. Heave....Heave....Heave The Physics Classroom says: Push on the ground, and it pushes back. In technical fields, this is known as the ground reaction force. It is a well-known truth of tug-of-war participants. The more force with which you push against the ground, the more force with which it pushes back on you. Do you want to win a tug-of-war? Then push on the ground with more force than the opposing team.
This ground reaction force is used by nearly every one of us on a daily basis. As we walk, as we run, as we jump and as we turn, we use the ground to influence our motion. Without action-reaction, walking, running and jumping would be impossible. This is one more example of physics for better living.
Hovercraft The Physics Classroom says: Simply stated, Newton's first law of motion claims:
An object at rest stays at rest unless acted upon by an unbalanced force. An object in motion continues in motion at the same speed and in the same direction unless acted upon by an unbalanced force.
This first law is often referred to as the law of inertia. The law of inertia is often demonstrated in physics class using a hovercraft. The hovercraft pictured here consists of a platform that a student sits upon. Air is blown through the platform into a plastic pocket beneath the hovercraft. The air provides a cushion for the hovercraft and its rider, reducing the amount of friction between the hovercraft and the floor. Once set in motion, the hovercraft moves at a nearly constant speed.
Friction! The Physics Classroom says: This sequence photography photo shows a hockey player moving across the ice. The distance traveled between each consecutive frame is relatively constant. The motion of an object in a straight line at a constant speed is an indicator that all the forces acting upon an object are balanced.
There is very little friction between metal skates and ice. As such very little forward force is needed to balance the friction force and to sustain the motion at a constant speed. Constant speed motion across ice requires very little effort.
Tug of War The Physics Classroom says: Force is a push or pull that is exerted upon an object as a result of its interaction with another object. A tug-of-war provides a great illustration of how object-to-object interactions lead to a force.
The participants push with their legs off the ground; the ground in turn pushes back on the participants.
The participants pull upon a rope; and the rope in turn pulls back on them.
The force of the participants pulling upon the rope is transmitted through the rope to the participants of the opposing team. The opposing team pulls back on the rope.
Participants - ground; participants - rope; rope - participants of the opposing team. These are the interactions that lead to forces. These interactions result in pushes and pulls upon the objects involved.
Examples of Photos
The Physics Classroom says: It's a common question on physics tests:
Splat!
"A very unfortunate bug collides with the windshield of a high speed car. What encounters the greatest force - the bug or the windshield."
Don't fall for this one! Think Newton's third law! Think "equal". For every action, there is an EQUAL and opposite reaction. The force of the bug on the windshield is EQUAL to the force of the windshield on the bug. EQUAL
Skeptics will (and should) ask, "How can that be? The bug splatters all over the windshield and there is no noticeable detection in the speed of the car." With this statement, the subject was changed from Newton's third law to Newton's second law. The forces on the two interacting objects are equal, but the accelerations resulting from those forces are not. The bug encounters an enormous acceleration - not because of a greater force, but rather because of its relatively smaller mass. And as for the splattering - bugs do that sort of thing.
Heave....Heave....Heave
The Physics Classroom says: Push on the ground, and it pushes back. In technical fields, this is known as the ground reaction force. It is a well-known truth of tug-of-war participants. The more force with which you push against the ground, the more force with which it pushes back on you. Do you want to win a tug-of-war? Then push on the ground with more force than the opposing team.
This ground reaction force is used by nearly every one of us on a daily basis. As we walk, as we run, as we jump and as we turn, we use the ground to influence our motion. Without action-reaction, walking, running and jumping would be impossible. This is one more example of physics for better living.
Hovercraft
The Physics Classroom says: Simply stated, Newton's first law of motion claims:
An object at rest stays at rest unless acted upon by an unbalanced force. An object in motion continues in motion at the same speed and in the same direction unless acted upon by an unbalanced force.
This first law is often referred to as the law of inertia. The law of inertia is often demonstrated in physics class using a hovercraft. The hovercraft pictured here consists of a platform that a student sits upon. Air is blown through the platform into a plastic pocket beneath the hovercraft. The air provides a cushion for the hovercraft and its rider, reducing the amount of friction between the hovercraft and the floor. Once set in motion, the hovercraft moves at a nearly constant speed.
Friction!
The Physics Classroom says: This sequence photography photo shows a hockey player moving across the ice. The distance traveled between each consecutive frame is relatively constant. The motion of an object in a straight line at a constant speed is an indicator that all the forces acting upon an object are balanced.
There is very little friction between metal skates and ice. As such very little forward force is needed to balance the friction force and to sustain the motion at a constant speed. Constant speed motion across ice requires very little effort.
Tug of War
The Physics Classroom says: Force is a push or pull that is exerted upon an object as a result of its interaction with another object. A tug-of-war provides a great illustration of how object-to-object interactions lead to a force.
The participants push with their legs off the ground; the ground in turn pushes back on the participants.
The participants pull upon a rope; and the rope in turn pulls back on them.
The force of the participants pulling upon the rope is transmitted through the rope to the participants of the opposing team. The opposing team pulls back on the rope.
Participants - ground; participants - rope; rope - participants of the opposing team. These are the interactions that lead to forces. These interactions result in pushes and pulls upon the objects involved.